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Commit 8aa08824 authored by Kevin Modzelewski's avatar Kevin Modzelewski
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Delete capi/float.cpp and move its contents to runtime/float.cpp 

I don't remember the original reasoning for having the separate capi/float.cpp,
and all the other runtime/ files have their CAPI methods inline.
parent fb62db02
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Showing with 563 additions and 674 deletions
src/CMakeLists.txt
View file @ 8aa08824
......@@ -30,7 +30,6 @@ add_library(PYSTON_OBJECTS OBJECT ${OPTIONAL_SRCS}
capi/codecs.cpp
capi/descrobject.cpp
capi/errors.cpp
capi/float.cpp
capi/modsupport.cpp
capi/object.cpp
capi/typeobject.cpp
......
src/capi/float.cpp deleted 100644 → 0
View file @ fb62db02
// Copyright (c) 2014-2015 Dropbox, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// This file is mostly copied from CPython
#include <cfloat>
#include "Python.h"
#include "core/types.h"
#include "runtime/types.h"
namespace pyston {
extern "C" {
typedef enum { unknown_format, ieee_big_endian_format, ieee_little_endian_format } float_format_type;
static float_format_type _detect_double_format() {
float_format_type format;
#if SIZEOF_DOUBLE == 8
{
double x = 9006104071832581.0;
if (memcmp(&x, "\x43\x3f\xff\x01\x02\x03\x04\x05", 8) == 0)
format = ieee_big_endian_format;
else if (memcmp(&x, "\x05\x04\x03\x02\x01\xff\x3f\x43", 8) == 0)
format = ieee_little_endian_format;
else
format = unknown_format;
}
#else
format = unknown_format;
#endif
return format;
}
static float_format_type _detect_float_format() {
float_format_type format;
#if SIZEOF_FLOAT == 4
{
float y = 16711938.0;
if (memcmp(&y, "\x4b\x7f\x01\x02", 4) == 0)
format = ieee_big_endian_format;
else if (memcmp(&y, "\x02\x01\x7f\x4b", 4) == 0)
format = ieee_little_endian_format;
else
format = unknown_format;
}
#else
format = unknown_format;
#endif
return format;
}
static float_format_type double_format, float_format;
static float_format_type detected_double_format = _detect_double_format(),
detected_float_format = _detect_float_format();
static PyObject* float_getformat(PyTypeObject* v, PyObject* arg) noexcept {
float_format_type r;
BoxedString* str = static_cast<BoxedString*>(arg);
if (!PyString_Check(arg)) {
PyErr_Format(PyExc_TypeError, "__getformat__() argument must be string, not %.500s", Py_TYPE(arg)->tp_name);
return NULL;
}
if (str->s == "double") {
r = double_format;
} else if (str->s == "float") {
r = float_format;
} else {
PyErr_SetString(PyExc_ValueError, "__getformat__() argument 1 must be "
"'double' or 'float'");
return NULL;
}
switch (r) {
case unknown_format:
return static_cast<PyObject*>(boxStrConstant("unknown"));
case ieee_little_endian_format:
return static_cast<PyObject*>(boxStrConstant("IEEE, little-endian"));
case ieee_big_endian_format:
return static_cast<PyObject*>(boxStrConstant("IEEE, big-endian"));
default:
Py_FatalError("insane float_format or double_format");
return NULL;
}
}
PyDoc_STRVAR(float_getformat_doc, "float.__getformat__(typestr) -> string\n"
"\n"
"You probably don't want to use this function. It exists mainly to be\n"
"used in Python's test suite.\n"
"\n"
"typestr must be 'double' or 'float'. This function returns whichever of\n"
"'unknown', 'IEEE, big-endian' or 'IEEE, little-endian' best describes the\n"
"format of floating point numbers used by the C type named by typestr.");
static PyObject* float_setformat(PyTypeObject* v, PyObject* args) noexcept {
char* typestr;
char* format;
float_format_type f;
float_format_type detected;
float_format_type* p;
if (!PyArg_ParseTuple(args, "ss:__setformat__", &typestr, &format))
return NULL;
if (strcmp(typestr, "double") == 0) {
p = &double_format;
detected = detected_double_format;
} else if (strcmp(typestr, "float") == 0) {
p = &float_format;
detected = detected_float_format;
} else {
PyErr_SetString(PyExc_ValueError, "__setformat__() argument 1 must "
"be 'double' or 'float'");
return NULL;
}
if (strcmp(format, "unknown") == 0) {
f = unknown_format;
} else if (strcmp(format, "IEEE, little-endian") == 0) {
f = ieee_little_endian_format;
} else if (strcmp(format, "IEEE, big-endian") == 0) {
f = ieee_big_endian_format;
} else {
PyErr_SetString(PyExc_ValueError, "__setformat__() argument 2 must be "
"'unknown', 'IEEE, little-endian' or "
"'IEEE, big-endian'");
return NULL;
}
if (f != unknown_format && f != detected) {
PyErr_Format(PyExc_ValueError, "can only set %s format to 'unknown' or the "
"detected platform value",
typestr);
return NULL;
}
*p = f;
Py_RETURN_NONE;
}
/*----------------------------------------------------------------------------
* _PyFloat_{Pack,Unpack}{4,8}. See floatobject.h.
*/
extern "C" int _PyFloat_Pack4(double x, unsigned char* p, int le) noexcept {
if (float_format == unknown_format) {
unsigned char sign;
int e;
double f;
unsigned int fbits;
int incr = 1;
if (le) {
p += 3;
incr = -1;
}
if (x < 0) {
sign = 1;
x = -x;
} else
sign = 0;
f = frexp(x, &e);
/* Normalize f to be in the range [1.0, 2.0) */
if (0.5 <= f && f < 1.0) {
f *= 2.0;
e--;
} else if (f == 0.0)
e = 0;
else {
PyErr_SetString(PyExc_SystemError, "frexp() result out of range");
return -1;
}
if (e >= 128)
goto Overflow;
else if (e < -126) {
/* Gradual underflow */
f = ldexp(f, 126 + e);
e = 0;
} else if (!(e == 0 && f == 0.0)) {
e += 127;
f -= 1.0; /* Get rid of leading 1 */
}
f *= 8388608.0; /* 2**23 */
fbits = (unsigned int)(f + 0.5); /* Round */
assert(fbits <= 8388608);
if (fbits >> 23) {
/* The carry propagated out of a string of 23 1 bits. */
fbits = 0;
++e;
if (e >= 255)
goto Overflow;
}
/* First byte */
*p = (sign << 7) | (e >> 1);
p += incr;
/* Second byte */
*p = (char)(((e & 1) << 7) | (fbits >> 16));
p += incr;
/* Third byte */
*p = (fbits >> 8) & 0xFF;
p += incr;
/* Fourth byte */
*p = fbits & 0xFF;
/* Done */
return 0;
} else {
float y = (float)x;
const char* s = (char*)&y;
int i, incr = 1;
if (Py_IS_INFINITY(y) && !Py_IS_INFINITY(x))
goto Overflow;
if ((float_format == ieee_little_endian_format && !le) || (float_format == ieee_big_endian_format && le)) {
p += 3;
incr = -1;
}
for (i = 0; i < 4; i++) {
*p = *s++;
p += incr;
}
return 0;
}
Overflow:
PyErr_SetString(PyExc_OverflowError, "float too large to pack with f format");
return -1;
}
extern "C" int _PyFloat_Pack8(double x, unsigned char* p, int le) noexcept {
if (double_format == unknown_format) {
unsigned char sign;
int e;
double f;
unsigned int fhi, flo;
int incr = 1;
if (le) {
p += 7;
incr = -1;
}
if (x < 0) {
sign = 1;
x = -x;
} else
sign = 0;
f = frexp(x, &e);
/* Normalize f to be in the range [1.0, 2.0) */
if (0.5 <= f && f < 1.0) {
f *= 2.0;
e--;
} else if (f == 0.0)
e = 0;
else {
PyErr_SetString(PyExc_SystemError, "frexp() result out of range");
return -1;
}
if (e >= 1024)
goto Overflow;
else if (e < -1022) {
/* Gradual underflow */
f = ldexp(f, 1022 + e);
e = 0;
} else if (!(e == 0 && f == 0.0)) {
e += 1023;
f -= 1.0; /* Get rid of leading 1 */
}
/* fhi receives the high 28 bits; flo the low 24 bits (== 52 bits) */
f *= 268435456.0; /* 2**28 */
fhi = (unsigned int)f; /* Truncate */
assert(fhi < 268435456);
f -= (double)fhi;
f *= 16777216.0; /* 2**24 */
flo = (unsigned int)(f + 0.5); /* Round */
assert(flo <= 16777216);
if (flo >> 24) {
/* The carry propagated out of a string of 24 1 bits. */
flo = 0;
++fhi;
if (fhi >> 28) {
/* And it also progagated out of the next 28 bits. */
fhi = 0;
++e;
if (e >= 2047)
goto Overflow;
}
}
/* First byte */
*p = (sign << 7) | (e >> 4);
p += incr;
/* Second byte */
*p = (unsigned char)(((e & 0xF) << 4) | (fhi >> 24));
p += incr;
/* Third byte */
*p = (fhi >> 16) & 0xFF;
p += incr;
/* Fourth byte */
*p = (fhi >> 8) & 0xFF;
p += incr;
/* Fifth byte */
*p = fhi & 0xFF;
p += incr;
/* Sixth byte */
*p = (flo >> 16) & 0xFF;
p += incr;
/* Seventh byte */
*p = (flo >> 8) & 0xFF;
p += incr;
/* Eighth byte */
*p = flo & 0xFF;
/* p += incr; Unneeded (for now) */
/* Done */
return 0;
Overflow:
PyErr_SetString(PyExc_OverflowError, "float too large to pack with d format");
return -1;
} else {
const char* s = (char*)&x;
int i, incr = 1;
if ((double_format == ieee_little_endian_format && !le) || (double_format == ieee_big_endian_format && le)) {
p += 7;
incr = -1;
}
for (i = 0; i < 8; i++) {
*p = *s++;
p += incr;
}
return 0;
}
}
double _PyFloat_Unpack4(const unsigned char* p, int le) noexcept {
if (float_format == unknown_format) {
unsigned char sign;
int e;
unsigned int f;
double x;
int incr = 1;
if (le) {
p += 3;
incr = -1;
}
/* First byte */
sign = (*p >> 7) & 1;
e = (*p & 0x7F) << 1;
p += incr;
/* Second byte */
e |= (*p >> 7) & 1;
f = (*p & 0x7F) << 16;
p += incr;
if (e == 255) {
PyErr_SetString(PyExc_ValueError, "can't unpack IEEE 754 special value "
"on non-IEEE platform");
return -1;
}
/* Third byte */
f |= *p << 8;
p += incr;
/* Fourth byte */
f |= *p;
x = (double)f / 8388608.0;
/* XXX This sadly ignores Inf/NaN issues */
if (e == 0)
e = -126;
else {
x += 1.0;
e -= 127;
}
x = ldexp(x, e);
if (sign)
x = -x;
return x;
} else {
float x;
if ((float_format == ieee_little_endian_format && !le) || (float_format == ieee_big_endian_format && le)) {
char buf[4];
char* d = &buf[3];
int i;
for (i = 0; i < 4; i++) {
*d-- = *p++;
}
memcpy(&x, buf, 4);
} else {
memcpy(&x, p, 4);
}
return x;
}
}
double _PyFloat_Unpack8(const unsigned char* p, int le) noexcept {
if (double_format == unknown_format) {
unsigned char sign;
int e;
unsigned int fhi, flo;
double x;
int incr = 1;
if (le) {
p += 7;
incr = -1;
}
/* First byte */
sign = (*p >> 7) & 1;
e = (*p & 0x7F) << 4;
p += incr;
/* Second byte */
e |= (*p >> 4) & 0xF;
fhi = (*p & 0xF) << 24;
p += incr;
if (e == 2047) {
PyErr_SetString(PyExc_ValueError, "can't unpack IEEE 754 special value "
"on non-IEEE platform");
return -1.0;
}
/* Third byte */
fhi |= *p << 16;
p += incr;
/* Fourth byte */
fhi |= *p << 8;
p += incr;
/* Fifth byte */
fhi |= *p;
p += incr;
/* Sixth byte */
flo = *p << 16;
p += incr;
/* Seventh byte */
flo |= *p << 8;
p += incr;
/* Eighth byte */
flo |= *p;
x = (double)fhi + (double)flo / 16777216.0; /* 2**24 */
x /= 268435456.0; /* 2**28 */
if (e == 0)
e = -1022;
else {
x += 1.0;
e -= 1023;
}
x = ldexp(x, e);
if (sign)
x = -x;
return x;
} else {
double x;
if ((double_format == ieee_little_endian_format && !le) || (double_format == ieee_big_endian_format && le)) {
char buf[8];
char* d = &buf[7];
int i;
for (i = 0; i < 8; i++) {
*d-- = *p++;
}
memcpy(&x, buf, 8);
} else {
memcpy(&x, p, 8);
}
return x;
}
}
#if DBL_MANT_DIG == 53
#define FIVE_POW_LIMIT 22
#else
#error "C doubles do not appear to be IEEE 754 binary64 format"
#endif
PyObject* _Py_double_round(double x, int ndigits) noexcept {
double rounded, m;
Py_ssize_t buflen, mybuflen = 100;
char* buf, *buf_end, shortbuf[100], * mybuf = shortbuf;
int decpt, sign, val, halfway_case;
PyObject* result = NULL;
_Py_SET_53BIT_PRECISION_HEADER;
/* Easy path for the common case ndigits == 0. */
if (ndigits == 0) {
rounded = round(x);
if (fabs(rounded - x) == 0.5)
/* halfway between two integers; use round-away-from-zero */
rounded = x + (x > 0.0 ? 0.5 : -0.5);
return PyFloat_FromDouble(rounded);
}
/* The basic idea is very simple: convert and round the double to a
decimal string using _Py_dg_dtoa, then convert that decimal string
back to a double with _Py_dg_strtod. There's one minor difficulty:
Python 2.x expects round to do round-half-away-from-zero, while
_Py_dg_dtoa does round-half-to-even. So we need some way to detect
and correct the halfway cases.
Detection: a halfway value has the form k * 0.5 * 10**-ndigits for
some odd integer k. Or in other words, a rational number x is
exactly halfway between two multiples of 10**-ndigits if its
2-valuation is exactly -ndigits-1 and its 5-valuation is at least
-ndigits. For ndigits >= 0 the latter condition is automatically
satisfied for a binary float x, since any such float has
nonnegative 5-valuation. For 0 > ndigits >= -22, x needs to be an
integral multiple of 5**-ndigits; we can check this using fmod.
For -22 > ndigits, there are no halfway cases: 5**23 takes 54 bits
to represent exactly, so any odd multiple of 0.5 * 10**n for n >=
23 takes at least 54 bits of precision to represent exactly.
Correction: a simple strategy for dealing with halfway cases is to
(for the halfway cases only) call _Py_dg_dtoa with an argument of
ndigits+1 instead of ndigits (thus doing an exact conversion to
decimal), round the resulting string manually, and then convert
back using _Py_dg_strtod.
*/
/* nans, infinities and zeros should have already been dealt
with by the caller (in this case, builtin_round) */
assert(std::isfinite(x) && x != 0.0);
/* find 2-valuation val of x */
m = frexp(x, &val);
while (m != floor(m)) {
m *= 2.0;
val--;
}
/* determine whether this is a halfway case */
if (val == -ndigits - 1) {
if (ndigits >= 0)
halfway_case = 1;
else if (ndigits >= -FIVE_POW_LIMIT) {
double five_pow = 1.0;
int i;
for (i = 0; i < -ndigits; i++)
five_pow *= 5.0;
halfway_case = fmod(x, five_pow) == 0.0;
} else
halfway_case = 0;
} else
halfway_case = 0;
/* round to a decimal string; use an extra place for halfway case */
_Py_SET_53BIT_PRECISION_START;
buf = _Py_dg_dtoa(x, 3, ndigits + halfway_case, &decpt, &sign, &buf_end);
_Py_SET_53BIT_PRECISION_END;
if (buf == NULL) {
PyErr_NoMemory();
return NULL;
}
buflen = buf_end - buf;
/* in halfway case, do the round-half-away-from-zero manually */
if (halfway_case) {
int i, carry;
/* sanity check: _Py_dg_dtoa should not have stripped
any zeros from the result: there should be exactly
ndigits+1 places following the decimal point, and
the last digit in the buffer should be a '5'.*/
assert(buflen - decpt == ndigits + 1);
assert(buf[buflen - 1] == '5');
/* increment and shift right at the same time. */
decpt += 1;
carry = 1;
for (i = buflen - 1; i-- > 0;) {
carry += buf[i] - '0';
buf[i + 1] = carry % 10 + '0';
carry /= 10;
}
buf[0] = carry + '0';
}
/* Get new buffer if shortbuf is too small. Space needed <= buf_end -
buf + 8: (1 extra for '0', 1 for sign, 5 for exp, 1 for '\0'). */
if (buflen + 8 > mybuflen) {
mybuflen = buflen + 8;
mybuf = (char*)PyMem_Malloc(mybuflen);
if (mybuf == NULL) {
PyErr_NoMemory();
goto exit;
}
}
/* copy buf to mybuf, adding exponent, sign and leading 0 */
PyOS_snprintf(mybuf, mybuflen, "%s0%se%d", (sign ? "-" : ""), buf, decpt - (int)buflen);
/* and convert the resulting string back to a double */
errno = 0;
_Py_SET_53BIT_PRECISION_START;
rounded = _Py_dg_strtod(mybuf, NULL);
_Py_SET_53BIT_PRECISION_END;
if (errno == ERANGE && fabs(rounded) >= 1.)
PyErr_SetString(PyExc_OverflowError, "rounded value too large to represent");
else
result = PyFloat_FromDouble(rounded);
/* done computing value; now clean up */
if (mybuf != shortbuf)
PyMem_Free(mybuf);
exit:
_Py_dg_freedtoa(buf);
return result;
}
}
}
src/runtime/float.cpp
View file @ 8aa08824
......@@ -12,6 +12,7 @@
// See the License for the specific language governing permissions and
// limitations under the License.
#include <cfloat>
#include <cmath>
#include <cstring>
......@@ -833,6 +834,568 @@ const char* floatGetFormatDoc = "float.__getformat__(typestr) -> string\n"
"'unknown', 'IEEE, big-endian' or 'IEEE, little-endian' best describes the\n"
"format of floating point numbers used by the C type named by typestr.";
static PyObject* float_setformat(PyTypeObject* v, PyObject* args) noexcept {
char* typestr;
char* format;
float_format_type f;
float_format_type detected;
float_format_type* p;
if (!PyArg_ParseTuple(args, "ss:__setformat__", &typestr, &format))
return NULL;
if (strcmp(typestr, "double") == 0) {
p = &double_format;
detected = detected_double_format;
} else if (strcmp(typestr, "float") == 0) {
p = &float_format;
detected = detected_float_format;
} else {
PyErr_SetString(PyExc_ValueError, "__setformat__() argument 1 must "
"be 'double' or 'float'");
return NULL;
}
if (strcmp(format, "unknown") == 0) {
f = unknown_format;
} else if (strcmp(format, "IEEE, little-endian") == 0) {
f = ieee_little_endian_format;
} else if (strcmp(format, "IEEE, big-endian") == 0) {
f = ieee_big_endian_format;
} else {
PyErr_SetString(PyExc_ValueError, "__setformat__() argument 2 must be "
"'unknown', 'IEEE, little-endian' or "
"'IEEE, big-endian'");
return NULL;
}
if (f != unknown_format && f != detected) {
PyErr_Format(PyExc_ValueError, "can only set %s format to 'unknown' or the "
"detected platform value",
typestr);
return NULL;
}
*p = f;
Py_RETURN_NONE;
}
/*----------------------------------------------------------------------------
* _PyFloat_{Pack,Unpack}{4,8}. See floatobject.h.
*/
extern "C" int _PyFloat_Pack4(double x, unsigned char* p, int le) noexcept {
if (float_format == unknown_format) {
unsigned char sign;
int e;
double f;
unsigned int fbits;
int incr = 1;
if (le) {
p += 3;
incr = -1;
}
if (x < 0) {
sign = 1;
x = -x;
} else
sign = 0;
f = frexp(x, &e);
/* Normalize f to be in the range [1.0, 2.0) */
if (0.5 <= f && f < 1.0) {
f *= 2.0;
e--;
} else if (f == 0.0)
e = 0;
else {
PyErr_SetString(PyExc_SystemError, "frexp() result out of range");
return -1;
}
if (e >= 128)
goto Overflow;
else if (e < -126) {
/* Gradual underflow */
f = ldexp(f, 126 + e);
e = 0;
} else if (!(e == 0 && f == 0.0)) {
e += 127;
f -= 1.0; /* Get rid of leading 1 */
}
f *= 8388608.0; /* 2**23 */
fbits = (unsigned int)(f + 0.5); /* Round */
assert(fbits <= 8388608);
if (fbits >> 23) {
/* The carry propagated out of a string of 23 1 bits. */
fbits = 0;
++e;
if (e >= 255)
goto Overflow;
}
/* First byte */
*p = (sign << 7) | (e >> 1);
p += incr;
/* Second byte */
*p = (char)(((e & 1) << 7) | (fbits >> 16));
p += incr;
/* Third byte */
*p = (fbits >> 8) & 0xFF;
p += incr;
/* Fourth byte */
*p = fbits & 0xFF;
/* Done */
return 0;
} else {
float y = (float)x;
const char* s = (char*)&y;
int i, incr = 1;
if (Py_IS_INFINITY(y) && !Py_IS_INFINITY(x))
goto Overflow;
if ((float_format == ieee_little_endian_format && !le) || (float_format == ieee_big_endian_format && le)) {
p += 3;
incr = -1;
}
for (i = 0; i < 4; i++) {
*p = *s++;
p += incr;
}
return 0;
}
Overflow:
PyErr_SetString(PyExc_OverflowError, "float too large to pack with f format");
return -1;
}
extern "C" int _PyFloat_Pack8(double x, unsigned char* p, int le) noexcept {
if (double_format == unknown_format) {
unsigned char sign;
int e;
double f;
unsigned int fhi, flo;
int incr = 1;
if (le) {
p += 7;
incr = -1;
}
if (x < 0) {
sign = 1;
x = -x;
} else
sign = 0;
f = frexp(x, &e);
/* Normalize f to be in the range [1.0, 2.0) */
if (0.5 <= f && f < 1.0) {
f *= 2.0;
e--;
} else if (f == 0.0)
e = 0;
else {
PyErr_SetString(PyExc_SystemError, "frexp() result out of range");
return -1;
}
if (e >= 1024)
goto Overflow;
else if (e < -1022) {
/* Gradual underflow */
f = ldexp(f, 1022 + e);
e = 0;
} else if (!(e == 0 && f == 0.0)) {
e += 1023;
f -= 1.0; /* Get rid of leading 1 */
}
/* fhi receives the high 28 bits; flo the low 24 bits (== 52 bits) */
f *= 268435456.0; /* 2**28 */
fhi = (unsigned int)f; /* Truncate */
assert(fhi < 268435456);
f -= (double)fhi;
f *= 16777216.0; /* 2**24 */
flo = (unsigned int)(f + 0.5); /* Round */
assert(flo <= 16777216);
if (flo >> 24) {
/* The carry propagated out of a string of 24 1 bits. */
flo = 0;
++fhi;
if (fhi >> 28) {
/* And it also progagated out of the next 28 bits. */
fhi = 0;
++e;
if (e >= 2047)
goto Overflow;
}
}
/* First byte */
*p = (sign << 7) | (e >> 4);
p += incr;
/* Second byte */
*p = (unsigned char)(((e & 0xF) << 4) | (fhi >> 24));
p += incr;
/* Third byte */
*p = (fhi >> 16) & 0xFF;
p += incr;
/* Fourth byte */
*p = (fhi >> 8) & 0xFF;
p += incr;
/* Fifth byte */
*p = fhi & 0xFF;
p += incr;
/* Sixth byte */
*p = (flo >> 16) & 0xFF;
p += incr;
/* Seventh byte */
*p = (flo >> 8) & 0xFF;
p += incr;
/* Eighth byte */
*p = flo & 0xFF;
/* p += incr; Unneeded (for now) */
/* Done */
return 0;
Overflow:
PyErr_SetString(PyExc_OverflowError, "float too large to pack with d format");
return -1;
} else {
const char* s = (char*)&x;
int i, incr = 1;
if ((double_format == ieee_little_endian_format && !le) || (double_format == ieee_big_endian_format && le)) {
p += 7;
incr = -1;
}
for (i = 0; i < 8; i++) {
*p = *s++;
p += incr;
}
return 0;
}
}
extern "C" double _PyFloat_Unpack4(const unsigned char* p, int le) noexcept {
if (float_format == unknown_format) {
unsigned char sign;
int e;
unsigned int f;
double x;
int incr = 1;
if (le) {
p += 3;
incr = -1;
}
/* First byte */
sign = (*p >> 7) & 1;
e = (*p & 0x7F) << 1;
p += incr;
/* Second byte */
e |= (*p >> 7) & 1;
f = (*p & 0x7F) << 16;
p += incr;
if (e == 255) {
PyErr_SetString(PyExc_ValueError, "can't unpack IEEE 754 special value "
"on non-IEEE platform");
return -1;
}
/* Third byte */
f |= *p << 8;
p += incr;
/* Fourth byte */
f |= *p;
x = (double)f / 8388608.0;
/* XXX This sadly ignores Inf/NaN issues */
if (e == 0)
e = -126;
else {
x += 1.0;
e -= 127;
}
x = ldexp(x, e);
if (sign)
x = -x;
return x;
} else {
float x;
if ((float_format == ieee_little_endian_format && !le) || (float_format == ieee_big_endian_format && le)) {
char buf[4];
char* d = &buf[3];
int i;
for (i = 0; i < 4; i++) {
*d-- = *p++;
}
memcpy(&x, buf, 4);
} else {
memcpy(&x, p, 4);
}
return x;
}
}
extern "C" double _PyFloat_Unpack8(const unsigned char* p, int le) noexcept {
if (double_format == unknown_format) {
unsigned char sign;
int e;
unsigned int fhi, flo;
double x;
int incr = 1;
if (le) {
p += 7;
incr = -1;
}
/* First byte */
sign = (*p >> 7) & 1;
e = (*p & 0x7F) << 4;
p += incr;
/* Second byte */
e |= (*p >> 4) & 0xF;
fhi = (*p & 0xF) << 24;
p += incr;
if (e == 2047) {
PyErr_SetString(PyExc_ValueError, "can't unpack IEEE 754 special value "
"on non-IEEE platform");
return -1.0;
}
/* Third byte */
fhi |= *p << 16;
p += incr;
/* Fourth byte */
fhi |= *p << 8;
p += incr;
/* Fifth byte */
fhi |= *p;
p += incr;
/* Sixth byte */
flo = *p << 16;
p += incr;
/* Seventh byte */
flo |= *p << 8;
p += incr;
/* Eighth byte */
flo |= *p;
x = (double)fhi + (double)flo / 16777216.0; /* 2**24 */
x /= 268435456.0; /* 2**28 */
if (e == 0)
e = -1022;
else {
x += 1.0;
e -= 1023;
}
x = ldexp(x, e);
if (sign)
x = -x;
return x;
} else {
double x;
if ((double_format == ieee_little_endian_format && !le) || (double_format == ieee_big_endian_format && le)) {
char buf[8];
char* d = &buf[7];
int i;
for (i = 0; i < 8; i++) {
*d-- = *p++;
}
memcpy(&x, buf, 8);
} else {
memcpy(&x, p, 8);
}
return x;
}
}
#if DBL_MANT_DIG == 53
#define FIVE_POW_LIMIT 22
#else
#error "C doubles do not appear to be IEEE 754 binary64 format"
#endif
extern "C" PyObject* _Py_double_round(double x, int ndigits) noexcept {
double rounded, m;
Py_ssize_t buflen, mybuflen = 100;
char* buf, *buf_end, shortbuf[100], * mybuf = shortbuf;
int decpt, sign, val, halfway_case;
PyObject* result = NULL;
_Py_SET_53BIT_PRECISION_HEADER;
/* Easy path for the common case ndigits == 0. */
if (ndigits == 0) {
rounded = round(x);
if (fabs(rounded - x) == 0.5)
/* halfway between two integers; use round-away-from-zero */
rounded = x + (x > 0.0 ? 0.5 : -0.5);
return PyFloat_FromDouble(rounded);
}
/* The basic idea is very simple: convert and round the double to a
decimal string using _Py_dg_dtoa, then convert that decimal string
back to a double with _Py_dg_strtod. There's one minor difficulty:
Python 2.x expects round to do round-half-away-from-zero, while
_Py_dg_dtoa does round-half-to-even. So we need some way to detect
and correct the halfway cases.
Detection: a halfway value has the form k * 0.5 * 10**-ndigits for
some odd integer k. Or in other words, a rational number x is
exactly halfway between two multiples of 10**-ndigits if its
2-valuation is exactly -ndigits-1 and its 5-valuation is at least
-ndigits. For ndigits >= 0 the latter condition is automatically
satisfied for a binary float x, since any such float has
nonnegative 5-valuation. For 0 > ndigits >= -22, x needs to be an
integral multiple of 5**-ndigits; we can check this using fmod.
For -22 > ndigits, there are no halfway cases: 5**23 takes 54 bits
to represent exactly, so any odd multiple of 0.5 * 10**n for n >=
23 takes at least 54 bits of precision to represent exactly.
Correction: a simple strategy for dealing with halfway cases is to
(for the halfway cases only) call _Py_dg_dtoa with an argument of
ndigits+1 instead of ndigits (thus doing an exact conversion to
decimal), round the resulting string manually, and then convert
back using _Py_dg_strtod.
*/
/* nans, infinities and zeros should have already been dealt
with by the caller (in this case, builtin_round) */
assert(std::isfinite(x) && x != 0.0);
/* find 2-valuation val of x */
m = frexp(x, &val);
while (m != floor(m)) {
m *= 2.0;
val--;
}
/* determine whether this is a halfway case */
if (val == -ndigits - 1) {
if (ndigits >= 0)
halfway_case = 1;
else if (ndigits >= -FIVE_POW_LIMIT) {
double five_pow = 1.0;
int i;
for (i = 0; i < -ndigits; i++)
five_pow *= 5.0;
halfway_case = fmod(x, five_pow) == 0.0;
} else
halfway_case = 0;
} else
halfway_case = 0;
/* round to a decimal string; use an extra place for halfway case */
_Py_SET_53BIT_PRECISION_START;
buf = _Py_dg_dtoa(x, 3, ndigits + halfway_case, &decpt, &sign, &buf_end);
_Py_SET_53BIT_PRECISION_END;
if (buf == NULL) {
PyErr_NoMemory();
return NULL;
}
buflen = buf_end - buf;
/* in halfway case, do the round-half-away-from-zero manually */
if (halfway_case) {
int i, carry;
/* sanity check: _Py_dg_dtoa should not have stripped
any zeros from the result: there should be exactly
ndigits+1 places following the decimal point, and
the last digit in the buffer should be a '5'.*/
assert(buflen - decpt == ndigits + 1);
assert(buf[buflen - 1] == '5');
/* increment and shift right at the same time. */
decpt += 1;
carry = 1;
for (i = buflen - 1; i-- > 0;) {
carry += buf[i] - '0';
buf[i + 1] = carry % 10 + '0';
carry /= 10;
}
buf[0] = carry + '0';
}
/* Get new buffer if shortbuf is too small. Space needed <= buf_end -
buf + 8: (1 extra for '0', 1 for sign, 5 for exp, 1 for '\0'). */
if (buflen + 8 > mybuflen) {
mybuflen = buflen + 8;
mybuf = (char*)PyMem_Malloc(mybuflen);
if (mybuf == NULL) {
PyErr_NoMemory();
goto exit;
}
}
/* copy buf to mybuf, adding exponent, sign and leading 0 */
PyOS_snprintf(mybuf, mybuflen, "%s0%se%d", (sign ? "-" : ""), buf, decpt - (int)buflen);
/* and convert the resulting string back to a double */
errno = 0;
_Py_SET_53BIT_PRECISION_START;
rounded = _Py_dg_strtod(mybuf, NULL);
_Py_SET_53BIT_PRECISION_END;
if (errno == ERANGE && fabs(rounded) >= 1.)
PyErr_SetString(PyExc_OverflowError, "rounded value too large to represent");
else
result = PyFloat_FromDouble(rounded);
/* done computing value; now clean up */
if (mybuf != shortbuf)
PyMem_Free(mybuf);
exit:
_Py_dg_freedtoa(buf);
return result;
}
void setupFloat() {
_addFunc("__add__", BOXED_FLOAT, (void*)floatAddFloat, (void*)floatAddInt, (void*)floatAdd);
float_cls->giveAttr("__radd__", float_cls->getattr("__add__"));
......
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